Geomagnetic Storms:Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm

Updated at: 2011 Oct 02 2200 UTC

Mid-latitudes

0-24 hr

24-48 hr

ACTIVE

15 %

05 %

MINOR

05 %

01 %

SEVERE

01 %

01 %

High latitudes

0-24 hr

24-48 hr

ACTIVE

15 %

05 %

MINOR

05 %

01 %

SEVERE

01 %

01 %

Sunday, Oct. 2, 2011

What's up in space

Turn your cell phone into a field-tested satellite tracker. Works for Android and iPhone.

CHINESE SPACE STATION: On Thursday, China launched an experimental space station named Tiangong-1 (Heavenly Palace-1). The 8.5-ton module, about the size of a railroad car, will remain in orbit for two years as Chinese spacecraft perform rendevous and docking maneuvers, and Chinese astronauts visit for weeks at a time--all good practice for a larger outpost in the future. Check Spaceweather's Satellite Tracker for sighting opportunities. You can also turn your smartphone into a Tiangong-1 tracker by downloading the Simple Flybys app.

DOUBLE ERUPTION: On October 1st around 10:17 UT, widely-spaced sunspots 1302 and 1305 erupted in quick succession, revealing a long-distance entanglement which was not obvious before. NASA's Solar Dynamics Observatory (SDO) recorded the double blast:

Since it was launched in 2010, SDO has observed many "entangled eruptions." Active regions far apart but linked by magnetic fields can explode one after another, with disturbances spreading around the stellar surface domino-style. Yesterday's eruption appears to be the latest example.

The part of the eruption centered on sunspot 1305 hurled a coronal mass ejection toward Earth. The relatively slow-moving (500 km/s) cloud is expected to reach our planet on Oct. 4th, possibly causing geomagnetic storms when it arrives. High-latitude sky watchers should be alert for auroras. Geomagnetic storm alerts:text, voice.

POWER LINES: There's more to this picture of yesterday's urban sunset over São Carlos, Brasil, than meets the eye. Beneath the image, photographer Gustavo Rojas discusses what's behind the power lines:

"The sun is the nearest star, and source of all energy that circulates in our planet," he says. "The electrical energy running through these power lines come from hydroelectric power plants where water move turbines; water can only exist in our planet because of the Sun's warmth. Ancient cultures worshipped the Sun, but modern man often forgets its intimate connection with life on Earth, which is smaller than the sunspots visible in this image."

Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.